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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Vliv vlastností vstupních materiálů na kvalitu architektonických betonů / Influence of input materials for quality architectural concrete

Ondryášová, Veronika January 2018 (has links)
This diploma thesis focuses on the influence of properties of feedstocks for the production of quality surfaces of architectural concrete. The introductory part describes the definition of architectural concrete with the advantages and disadvantages of its implementation. In the following chapters, the characteristics, the dosage or the chemical composition of the input materials are given. Besides the design of the mixture, important parameters for the creation of a quality surface of concrete are compaction, precise placement in formwork and subsequent treatment of the surface. Individual types of architectural concrete, their method of production with the examples belonging to concrete constructions are also given. In the practical part, 4 mixtures were designed, whose type or dosage of feedstocks was changed. In creating mixtures, emphasis was placed on minimal segregation of fresh concrete and the formation of pores on the surface of hardened concrete.
82

Vývoj anortitové keramiky / Development of anorthite ceramics

Toman, Boris January 2013 (has links)
When firing calcium ceramic materials creates a new crystalline phase anorthite. It can significantly improve the properties of ceramic body. This work deals with the possibilities of development anortitové ceramics using non-plastic raw materials, particularly alumina cement compared with conventional ceramics based on mullite.
83

Lehčené podlahy na bázi pěnobetonů a plynobetonů s využitím druhotných surovin / Lightweight floors based on aerated concrete and foam concrete with the use of secondary raw materials

Kapčuk, Pavel January 2014 (has links)
This thesis is oriented on development of new porous materials for industrial floors based foam concrete and not autoclaved aerated concrete with the possible use of secondary raw materials and natural lightweight aggregates instead of classic aggregates. The dry mixture should be stored in bags as ready to use with the addition only of water.
84

Hodnocení kvality nerezového vlnovce / Quality Assessment of Stainless Corrugated Tube

Vychopeň, Petr January 2016 (has links)
Stainless corrugated tubes are used in many applications, mainly in automotive industry, distribution of various media, ventilation etc. The first part of the thesis is focused on description of the corrugated tube, identification of differences between corrugated pipe and hose, recommended materials for production and characterization of main technical parameters. The general production process of stainless corrugated tubes and the most common tests of mechanical properties are described. The second part of the thesis is focused on the comparison of the level of quality of the selected raw materials and evaluates the impact of partially degraded tools on the surface texture of the corrugated tube. The last part presents the results of measurements and practical recommendations.
85

Vliv surovin na vzduchovou neprůzvučnost cihlářského střepu / The Effect of Raw Materials on Sound Insulation of Brick Body

Bosák, Filip January 2017 (has links)
Diploma thesis is concerned with opportunities of increase sound isolution index for bricks. In theoretical part is summary of present knowledge about acoustic properties ceramic body field and theoretical calculations and measuring sound insulation as well as. Practically part is divided on apply and basic research. Under apply research is experiment, that considers impact quantity of raw materials using at brick factory in the Holice on the most significant technological properties of plastic paste and brick body, additionaly with the considering chances of increase sound insulation index. In basic research is experiment, that evaluates impact common use domestic brick´s raw materials on sound insulation. Sound insulation is evaluated indirectly by transsmision rate of ultrasound in a both cases.
86

Propuesta de integración vertical hacia atrás de la empresa Alimencorp para lograr un crecimiento sostenido y mejorar su rentabilidad / Backward vertical integration proposal of the ALIMENCORP Company to achieve sustained growth and improve its profitability

Barragán Cornejo, Shoana de los Milagros, Burga Toledo, Henry Simón, Garro Lescano, Gregorio Roberto 07 January 2021 (has links)
El objetivo principal de este trabajo de investigación es el análisis de la propuesta de integración vertical hacia atrás de la empresa ALIMENCORP para lograr un crecimiento sostenido y mejorar su rentabilidad, tomando como líneas base sus capacidades y potencialidades, así como su conducta y rendimiento dentro del sector. Para el desarrollo de la investigación, se analizó el sector del rendering en el Perú que provee de insumos proteicos al sector de alimentos balanceados para la crianza intensiva y de mascotas; el mismo que cuenta como característica resaltante la restricción de materias primas. En este sentido, el desarrollo del análisis externo e interno, brindaron precisiones para la realización de análisis acerca de las oportunidades, amenazas, así como de las fortalezas y debilidades que determinan la conducta de las empresas dentro del sector. Después de un análisis profundo de lo expuesto en el párrafo anterior, se formularon varias estrategias, obteniendo el mayor puntaje la estrategia de integración vertical hacia atrás para hacer frente a la restricción de materias primas, reforzando la cadena de suministros de ALIMENCORP para alcanzar un crecimiento sostenido y mejorar su rentabilidad. La investigación concluye que la estrategia desarrollada es un acierto porque ALIMENCORP cuenta con fortalezas mayores frente a sus competidores. Finalmente, de acuerdo a la evaluación financiera realizada se obtiene un VAN positivo de S/. 1 819,077 soles sobre el WACC con una TIR del 33.05%, por lo que se concluye que el proyecto es viable y se recomienda su implementación. / The main objective of this research is the analysis of the proposal for backward vertical integration of the company ALIMENCORP to achieve sustained growth and improve its profitability, taking as baselines its capabilities and potential, as well as its conduct and performance within the sector. For the development of the research, the rendering sector in Peru that provides protein inputs to the balanced food sector for intensive breeding and pets was analyzed; the same one that has as an outstanding feature the restriction of raw materials. In this sense, the development of the external and internal analysis, provided details for the analysis of opportunities, threats, as well as the strengths and weaknesses that determine the conduct of companies within the sector. After an in-depth analysis of what was stated in the previous paragraph, several strategies were formulated, obtaining the highest score the backward vertical integration strategy to face the restriction of raw materials, reinforcing ALIMENCORP's supply chain to achieve a sustained growth and improve its profitability. The research concludes that the strategy developed is a success because ALIMENCORP has greater strengths compared to its competitors. Finally, according to the financial evaluation, a positive NPV of S/. 1 819,077 soles is obtained, over the WACC with an IRR of 33.05%, so it is concluded that the project is viable and its implementation is recommended. / Trabajo de investigación
87

Razvoj postupka sinteze polimernih mreža i linearnih polimera na osnovu siloksana / Development of the synthesis process of polymeric networks and linear polymer based on siloxane

Manjenčić Darko 28 September 2020 (has links)
<p>Istraživanja u okviru teze imaju za cilj dobijanje polimernih mreža kod kojih se regulacijom sirovinskog sastava i uslova sinteze mogu menjati svojstva siloksanskih materijala u skladu sa krajnjom primenom. Osnovni cilj istraživanja ove teze je razvoj novih postupaka sinteze hibridnih siloksanskih nanokompozita na osnovu različitih prekursora mreža. Takođe, ispitan je i uticaj različitih tipova funkcionalizacije povr&scaron;ina nanopunila silicijum(IV) oksida (sa hidrofobnom i hidrofilnom povr&scaron;inom) na svojstva kompozitnih materijala za specifične namene. Nanokompoziti na osnovu polimernih mreža se uglavnom koriste u onim primenama gde tradicionalne polimerne mreže ne mogu da zadovolje potrebe koje se pred njih stavljaju. Zato je potrebno razviti postupak koji bi omogućio dobijanje materijala na osnovu polimernih mreža sa pobolj&scaron;anim mehaničkim, elastičnim i toplotnim svojstvima. Motivacija je vođena potrebom razvoja novih kompozitnih materijala koji imaju jedinstvena mehanička, toplotna, termomehanička svojstva sa mogućno&scaron;ću da pomognu u re&scaron;avanju problema okoline, kao &scaron;to su problem sa prostorom, sa automobilima, u elektronici i infrastrukturi, i naravno, oni će biti veliki izazov u nauci materijala i industriji.<br />Siloksanske mreže su dobijene od &alpha;, &omega;-divinil poli(dimetilsiloksana) i poli(metil-hidrogen<br />siloksana) u odnosu 60/40; 50/50 i 40/60. Nanokompoziti su sintetisani dodavanjem različitih sadržaja nanopunila silicijum(IV) oksida (1, 2, 5, 10 i 20 mas.%). Za potvrdu pretpostavljenog mehanizma reakcije umrežavanja siloksana kori&scaron;ćena je FTIR spektroskopija. TEM analiza je kori&scaron;ćena za procenu topologije i potvrdila je dobru disperziju punila u polimernom matriksu. Dodavanje nanopunila pobolj&scaron;ava mehanička svojstva dobijenih materijala i povećanje vrednosti prekidne jačine za kompozite sa hidrofobnim silicijum(IV)oksidom je veće u poređenju sa kompozitima sa hidrofilnim punilima, &scaron;to je očekivano zbog bolje kompatibilnosti hidrofobne matrice i hidrofobnih punila. Termogravimetrijska analiza kori&scaron;ćena je za analizu uticaja vrste funkcionalizacije silicijum(IV) oksida na termičku stabilnost siloksanskih elastomernih<br />materijala. Kao &scaron;to se i očekivalo, porast sadržaja nanopunila povećava termičku stabilnost dobijenih hibridnih materijala. Uticaj punila na temperature faznog prelaza siloksanskih materijala analiziran je diferencijalnom skenirajućom kalorimetrijom. Zbog slabije kompatibilnosti hidrofilnog punila i hidrofobne matrice primećeno je smanjenje vrednosti Tm, a najmanja vrednost temperature topljenja primećena je za uzorak sa najvećim udelom hidrofilnog punila.<br />Uticaj nanopunila na mehaničke i termičke karakteristike dobijenih materijala biće detaljno analiziran, pri čemu je potvrđeno pobolj&scaron;anje mehaničkih svojstava siloksanskih elastomera dodatkom nanopunila. U cilju razvoja novih biokompatibilnih materijala i pobolj&scaron;anja svojstava biorazgradivosti siloksanskih materijala biće sintetisani ABA blok kopolimeri koji se sastoje od segmenata poli(dimetilsiloksana) i poli(laktida). Kao makroinicijator za sintezu blok kopolimera kori&scaron;ćen je polidimetilisiloksan, pa je polimerizacija laktida inicirana hidroksilnim grupama siloksana. Poli(laktid) se odlikuje veoma dobrim mehaničkim svojstvima i biorazgradivo&scaron;ću, dok se kopolimerizacijom sa siloksanima utiče na mehanička svojstva kao i na svojstva povr&scaron;ine sintetisanog kopolimera.</p> / <p>Research in the thesis aims to obtain polymeric networks in which the regulation of the raw<br />material composition and the conditions of the synthesis can alter the properties of the silicone<br />materials in accordance with the final application. The main goal of the research of this thesis is<br />the development of new procedures for the synthesis of hybrid silicone nanocomposites based on<br />different precursors. The influence of different types of surface functionalisation of nanofillers<br />(with hydrophobic and hydrophilic functionalised surface) on the properties of composite<br />materials for specific purposes was investigated. Nanocomposites based on polymer networks are<br />mainly used in those applications where traditional polymer networks cannot meet the needs that<br />are expected. It is therefore necessary to develop a process that would enable the production of<br />materials based on polymeric networks with improved mechanical, elastic and thermal properties.<br />Motivation is driven by the need to develop new composite materials that have unique<br />mechanical, thermal, thermo-mechanical properties with the ability to help solve environmental problems, such as space problems, cars, electronics and infrastructure, and of course they will be<br />a challenge in the material science and industry. Siloxane networks were prepared from &alpha;,&omega;-<br />divinyl poly(dimethylsiloxane) and poli(methyl-hydrogen siloxane) with a ratio 60/40; 50/50 and<br />40/60. Nanocomposites were synthesised with the addition of different contents of silica<br />nanofiller (1, 2 5, 10 and 20 wt%). For the confirmation of the presumed mechanism of siloxane<br />crosslinking reaction FTIR spectroscopy was used. TEM analysis was used for topology<br />evaluation and confirmed good dispersion of the fillers into the polymer matrix. Addition of<br />nanofillers increased the mechanical properties of obtained materials and greater increase of the<br />tensile strength for the composites based on hydrophobic silicon(IV)-oxide was assessed,<br />compared with the hydrophilic ones. It was expected due to better compatibility of hydrophobic<br />silicone matrix and hydrophobic filler particles. Thermogravimetric analysis was used for the<br />evaluation of the influence of the types of silicon(IV)oxide functionalisation, on the thermal<br />degradation of elastomeric materials. As it was expected the increases of nanofillers content<br />increased the thermal stability of obtained hybrid materials. The influence of fillers on the phase<br />transition temperatures of siloxanematerials was analysed with the differential scanning<br />calorimetry. Due to the lower compatibility of hydrophilic filler and hydrophobic matrix<br />decreasing of Tm values was observed, and the lowest value of melting temperature was noticed<br />for the sample with the highest loading of hydrophilic filler.<br />In order to develop new biocompatible materials and improve the biodegradability properties of<br />silicone materials, ABA types of block copolymers consisting of segments of<br />poly(dimethylsiloxane) and poly(lactide) was synthesized. As a macroinitiator for the synthesis of<br />the block copolymer, poly(dimethylisiloxane) was used, so the lactide polymerization starts from<br />the hydroxyl groups of siloxanes. Poly(lactide) is characterized by poor mechanical properties<br />and biodegradability, while copolymerization with silicones will affect the mechanical and<br />surface properties of the synthesized copolymer.</p>
88

Vývoj deskových materiálů na bázi druhotných surovin s dobrým poměrem tepelně izolačních a mechanických vlastností / Development of board materials based on secondary raw materials with a good ratio of thermal insulation and mechanical properties

Szotkowská, Michaela January 2022 (has links)
This diploma thesis focuses on the development of board materials based on secondary raw materials. The theoretical part outlines secondary raw materials and their further usage. In addition, the theoretical part deals with a description of protective panels with a focus on underlying profiles and requirements for protective panels in terms of thermal protection of buildings. At the end of the theoretical part, a multicriteria analysis and a method of assessing the impact of the products on the environment using LCA / EPD is described. The practical part describes input raw materials from various industries, test samples, their tests, and subsequent evaluation of required properties. Using the multi-criteria analysis, a board material with a favorable ratio between mechanical and thermal insulation properties was selected for the production of the base profile. Furthermore, the practical part deals with the production of the underlying profile, its testing, determining its competitiveness in the market, and a simplified description of its impact on the environment.
89

Stenbruk : Stenartefakter, råmaterial och mobilitet i östra Mellansverige under tidig- och mellanmesolitikum

Gustafsson Gillbrand, Patrik January 2018 (has links)
This thesis examines artefacts, raw materials and lithic technology between c. 9200–6200 cal BC in Eastern Central Sweden. The overall purpose of this study is to investigate when people first came to Eastern Central Sweden and where they came from. More precisely, it provides a typological, geo­graphical and chronological survey of artefacts and the use of different raw materials. The study deals with assemblages with artefacts from more than thirty archaeologically excavated sites and loose finds in Eastern Central Sweden. The objects consist of chubby pecked axes, core axes, flake axes, shaft hole picks, microliths and micro burins, points, burins, rulers, uni­facial blade core, conical cores, micro blade cores, blades, drills, re­touched blades and micro blades. The artefacts have been compared with established typologies and chronologies for the rest of the Nordic countries and to some extent Russia and the Baltic States. An analysis of different raw mater­ials present at Early and Middle Mesolithic sites in Eastern Central Sweden was also carried out. The materials are put into a chronological and geo­graphical context. The raw materials included in the study are the non-local rocks flint and Cambrian flint, as well as local raw materials such as quartz, greenstone, local vulcanite, mylonite and red porphyry. From 9200 cal BC there is evidence of the first groups of people in the area, just shortly after that the Weichselian ice cap had withdrawn. Throughout the period studied the artefacts as well as the non-local raw materials exhibit great similarities to those found in the western part of Sweden. The study also shows, regar­ding the use of different raw materials and presence of certain artefacts, that some major events took place, suggesting a new chronological time frame for the Early- and Middle Mesolithic periods. In addition, a discussion re­gar­­ding mobility and migration in Eastern Central Sweden during Early Post Glacial time is carried out.
90

Tension in Space

Snowdon, Roger J., III 06 May 2016 (has links)
No description available.

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